Nippon: Zaibatsu

Yes — at any moment on your turn you may spend 1 silk to gain 1 green money any number of times (silk can also be spent to temporarily boost R&D when building a Factory). (p. 8)

You must choose the action and take a Worker first, and you may not choose an action if you cannot perform it at least once; additionally you must pay the action in full and may not use resources gained during that action to pay for it. (p. 8)

Yes — you may spend silk (1/3/6) to temporarily increase your R&D level by 1/2/3 when building a Factory, and the rules also note you may spend 1/3/6 R&D tokens for the same temporary increase. (p. 8, p. 10)

You may not place Influence tokens that don’t match the level of the Goods, but you may replace your own Influence tokens (even ones you just placed) to gain region bonuses; follow the Local Market space limits and replacement rules for 2/3-player games. (p. 16)

During Consolidation you must discard all green resources and black cubes, then take a Favor token, gain Department bonuses and Income according to your Workers and levels, pay salaries, and return Workers as specified. (p. 17)

Trains grant their owner influence in a Region only if that player has at least one Influence token in that Region during scoring; otherwise those Trains grant no Influence. (p. 12, p. 18)